Getting a head of myself - Marshall 2204 JCM800 inspired build

[bepone]

- When you say separate capacitor for V1a and V1b I'm assuming you mean separate filter stages. But this isn't necessary.

ofcourse to improve things.

Plus we're not talking about a particularly high gain amp here. The general rule is two stages out of phase can share the same filter stage, which is what's happening in this case. So we should be fine. But I've seen a few Soldano amps and EVH amps share the same filter stage amongst 3/4 gain stages and be ok.

both amps are not so quiet, specially EVH , or peavey 5150

One of my amps has a 4 gain stage channel, it's in a fairly cramped chassis and it's pretty quiet. I didn't need DC heaters, it's AC but with DC elevated.

This is a JCM800, not a high gain amp by modern standards. We shouldn't have to go to extreme lengths to keep it quiet.

i already gave all the guidelines how to remove noise, it is ok to follow and it is ok not to follow them, for me is the same, i shared my system if will help the op

[bepone]

https://youtu.be/kyi_vo1MTOs
example of slo100 amp which i built p2p many years ago, following upstream signal topology and local star grounding, very quiet at the end

[Littlewyan]

https://youtu.be/kyi_vo1MTOs
example of slo100 amp which i built p2p many years ago, following upstream signal topology and local star grounding, very quiet at the end

Sounds awesome! Nice job. Hard work doing point to point so fair play!

[bepone]

Sounds awesome! Nice job. Hard work doing point to point so fair play!

thx , insoired by old radios and V4 ampeg signal upstream topology, where gnd for next capacitor and signal traveling together! actually i have found that p2p build is faster than other styles, you are using only leads of components and several wires suprisingly there was no any shrill and harsh components in the tone riding on the note, so 3D layout is interesting in many ways

[kuDo]

After an afternoon of desoldering an re-soldering en cutting wires and making a general mess of things.
I have finally finished my amp again.

The hiss issue in my amp is al down to the v1 grid stopper resistor.
It seems to become less when I put in lower value as oppose to the 68k that was in there.
At the moment there is a 2watt 10k resistor in there. But it is still hissing.

I isolated the first stage of the amp and amplified it with my test amp. My trusty old lm386 chip based ruby amp.
I could hear the same hiss as when it was in the completed amp.
I also fed the filaments with a stand alone dc battery. So no noise or hiss from there.

I do think that the 12ax7’s I have are quite microphonic. A they amplify the pinging noise the make when ticking on them with a stick.

But it seems to be impossible to have the amp without the hiss. I think it is time a arrange for a real jcm800, just to see wat those do, hiss wise. Maybe I am making to big of a fuss.

I can play my amp, and by no means is the hiss louder than the guitar signal, but In my mind I would think it could be quieter.

Thank you all for your feedback and suggestions!

[cys]

I would try going to a lower wattage resistor and shortening the legs on the resistor to an absolute minimum, the idea being to minimize the unshielded elements of this connection. I would also try grounding your shielded wire differently, perhaps at the other terminus, and find something that that looks like a quiet ground. Just ideas.

[ViperDoc]

I’m not certain where you are grounding your input wire shield. If it is on the preamp buss, try grounding the shield to its own chassis ground lug, and only at one end of the shield, of course.

[kuDo]

I’m not certain where you are grounding your input wire shield. If it is on the preamp buss, try grounding the shield to its own chassis ground lug, and only at one end of the shield, of course.

I have grounded the sleeve of the wire shield on the sleeve of the input jack, which in turn is the single connection of the circuit to the chasis.

[ViperDoc]

I have grounded the sleeve of the wire shield on the sleeve of the input jack, which in turn is the single connection of the circuit to the chasis.

Do you have continuity to ground with your shield? Your hum reduces greatly when you disconnect your second input switch ground. Look for ground loops or disconnects?